Electrically-heated container



Jan 6, 1931.

Filed Sept. 22, 192 2 Sheets-Sheet 1 Fz' .1. 15 v 5] 11 7 5 10 5 7ENVENTOFZ Mal 0 M 7AM m -w Jan 6, 1931.

H. o. SWOBODA ETAL ELECTRICALLY HEATED CONTAINER Filed Sept. 22, 192' 2Sheets-Sheet 2 I l l i INVENTOR i ate'nted diam 6, 193i UNETED STATESra'raar orsics HANS O. SWOBODA, F EDGEWOOD BORGUGH, ALLEGHENY COUNTY,AND WILLIAM F. METZGEB, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNORS TO B. 0.SWDBODA, INC., 013 PITTSBURGH, PENNSYLVANIA, A CORPORATION OFPENNSYLVANIA ELECTRICALLY-HEATED CONTAINER Application filed September22,1927. Serial No. 221,222.

Our invention relates to electric heaters and particularly to a methodand apparatus for heating containers of non-conducting material byutilizing commercial shapes of iron and steel as well as other metalsand alloys for the electric heater.

in heating containers, such as boilers, tanks, vats and the like, whenthe temperature of a mass of material is to be maintained substanmtiaily uniform and must not be materially exceeded due to the danger ofdecomposing said material, the selection of the proper type of electricheater presents considerable dilliculty. It is also important to reducethe time that must elapse during the interval of dissemination of thethermal energy from the electric heater throughout the entire mass ofmaterial to a minimum. 7

In the past, gas, oil, steam and electricity as have been used forheating such containers. In the caseof steam coils, in order to keep thetemperature of the same at or above the temperature desired in thematerial, it has been necessary to either provide a highenough,

2a steam pressure to insure that the steam traversing them is maintainedabove the predetermine temperature or super-heat the steam to permit atransfer of heat to the contents of the tank. Both the high enough steampressure as well as the super-heating of the steam in the plants wheresuch containers are used are very inconvenient to obtain, and have to rbe provided especially for the container, causing thereby considerableexpense. As an example, a heating coil for maintainin a nec-'essaryfltemper'ature of 450 F. throug out its lengthfinay require aninitial steam temperature of900 F.

Electric heaters which have been used for '40 this purpose usuallyconsist of special alloys,

either pipe, tubing, angles, channels, rods, bars, grids or any othercommercial shape of iron, steel, nickel or well-known alloys with alarge cross-sectional. area. This results in extremely rugged heatersproviding a large contact surface with the material, and permits a verylow temperature gradient, so that the said pipe, tubing, etc., can beplaced directly in engagement with the material without any furtherprotection and insulation. It can readily be seen that the replacementof the expensive nickel chromium allo by a cheap commercial shape ofiiron or the like, and the omission of any electric insulation as well asany means to protect the material 5 against excessive heat, result in anequipment not only very inexpensive with regard to first cost, but alsowith regard to repairs and re newals. In reality, repairs and renewalsare practically eliminated by the rugged construction and by the factthat repairs, if they should become necessary, can be made by theemployees of the shop where the container is installed without thepurchase of new expensive heating units.

Where pipe or tubing is utilized for the electric heater, it is possibleto heat and cool the material by the same pipes. For heating, electriccurrent is caused to traverse them, while for cooling, a cooling mediumsuch as air or water is circulated therethrough. This constructioneliminates, in a great many processes, the necessity for separateheating and cooling devices.

The electric heater for a container is usual- 5 1y made of severalsections and each section is sub-divided into a number of heating units.Each heating unit is preferably composed. of a number of straightlengths of the resistor material connected by return bends or noequivalent connections. Special care has been exercised that all pipesand their fittings when exposed to the vibrations of alternating currentare self-locking, so that they cannot come apart. This form of unit hasbeen selected, because it is non-inductive and easily constructed.However, heaters in helical or any other form may be employed, so longas they are non-inductive and can be placed into the container. Eachunit may rately, eit

be connected to an adjacent unit by a union or other form of coupling.If a number of these units are connected as a section, the ends of saidsections are provided with electrical terminals. These terminals whichextend above the surface of the material to be heated, are usually madeof larger cross-sectional area than the resistor material itself toprevent the generation of heat in the same.

The heater units are supported by insulators carried by angle or channelirons about the walls of the container but not fastened to the same. Ofcourse, they may also be installed in the center of the container incase this should become desirable in specific cases. Theupper ends ofthe units are secured in place by rods slidably movable throughinsulating bushings disposed 1n one of the iron shapes. These angles andchannel irons are fastened to a common support in such a manner that theentire electric heater can be removed from the container for clean: ingand repairing without emptying said container.

The heater sections are connected through the terminals to a source ofelectric energy. Usually, they are arranged in several groups; eachgroup being preferably controlled sepaier manually or automatically, formaintaining a predetermined uniform temperature. Different degrees ofheat may be obtained in each one of the sections by supplying eitherdifferent voltages from a transformer, or using a Y-delta switch, orboth.

In the foregoing, the invention has been described for containers withnon-conducting materials. However, it can also be applied to containerswith materials which are conductors of electricity. In such cases, theheaters have to be separated from the material by a shield, and thespace between the shield'and the container wall has to be filled with aninsulating fluid such as oil.

The accompanying drawings present a container for the heating ofnon-conducting material such as asphaltum. It is heated by a heatercomprising three sections, each section including a plurality of heatingunits disposed around the sides of the container. They are selectivelyconnected to an autotransformer with a Y-delta switch as describedabove.

The equipment shown in the drawings was selected in order to be able toshow specific details of construction. It is, however, understood thatany other design of container or electric heater as described in theforegoing is claimed as our invention.

In the drawings Fig. 1 is a sectional elevation of a container embodyingour invention.

Fig. 2 is a diagrammatical view of the electric heater.

Fig. 3 is a plan view of the heater unit, the upper guide being removed.

Fig. 4:.is an elevational view thereof.

Fig. 5 is a detail view, on an enlarged scale, and partly in section,showing the method of supporting and insulating the heater units.

Referring to Fig. 1, the container 1 is constituted by a wall 2, ajacket 3, a layer 4 of heat insulating material and a cover 5. Theinsulating material at is cut away near the top for defining space 6, inwhich electrical conductors 7 are disposed for connection to the heatingunits as hereinafter more fully described.

Conduits 8 extend through the jacket 3 into the space (S, for connectionto an external sourceof electromotive force.

A steel framework or slieleton 9 is sus pended from wall 2 by a collaror flange 14). Eyebolts 11 are provided in the collar 10 for enablingthe framework 9 and the supported heater units 12 to be bodily withdrawnfrom the container. The framework 9 comprises a shield 15 connected toflange 10 by angle irons 16 and which extends downwardly into thecontainer a sufficient distance for protecting the upper heater units 12from contact with the material lowered into the container. If desired,the shield 15 may be made solid without circulation holes and extend theentire length of the container for protecting the heater units fromengagement with the liquid within the container. 1f the liquid to beheated is an electrical conductor, the space between the shield and wallmay be filled with an insulating fluid such as oil. Where the nature ofthe material in the container permits of its direct engagement with theheater units, it is only necessary to extend the shield 15 down farenough to insure that objects lowered into the container shall be inalignment with the axis thereof. This feature is important where largepieces of material are lowered into the container.

Where the shield 15 extends downwardly into the container but a shortdistance, guard strips 17 are welded or riveted thereto. The guardstrips 17 extend downwardly substantially the entire length of thecontainer for supporting and protecting the heaterunits 12. The spacesbetween the guard strips permit the free circulation of the material inthe container into engagement with the heater units 12. Iron shapes18-19, 2021, 22 and 23 are supported on the outer surface of the shield15 and guard strips 17 for supporting, guiding and separating the heaterunits into three distinct sections-A, l5 and C respectively. Iron shape24 serves to guide terminals 32.

Referring to Figs. 3 to 5 inclusive, each of the heater units 12comprises a plurality of lengths of heater pipe 2:3,connectcd at theupper and lower ends by return bends 26 and 27, respectively. The numberof pipes 25 in each heater unit may be varied as desired. Insulators 28are mounted on the pipes for preventing them from coming into engagementwith each other in case of sired.

The outer pipes 25 in each section term1-' nate in a terminal pipe oflarger cross sectional area than the pipe sections themselves, in orderto prevent the vterminals from being heated to the same degree as arethe pipes 25. Each terminal pipe 30 is surmounted by a T 31 opposite tospace 6. As the heating sections A, B and C are disposed at differentlevels in the container 1, the terminal pipes 30 are of differentlengths in accordance with the position of the heating sectionscontrolled by them.

The top of the T 31 is provided with an electrical terminal 32 forconnection to electrical conductors. As shown in Fig. 3, special carehas been exercised that these terminals do not exceed in diameter theassociated pipe 25 with its fittings 27 and 31, avoiding thereby anywaste of space incident to the use of most electrical terminals. A pipe34 is connected to the T through a set of insulating flanges and washers35 and 36 in order that the pipe 34 shall not be charged with electriccurrent while the pipes 25 are used as electric heaters. By thisarrangement, the pipes 25 serve as heaters when elec trically ener ized,and as cooling coils when the cooling uid is passed through.

Each of the return bends 27 is deposited in a groove 37, in aninsulating block 38. The insulating block may be of slate, porcelain, orany other suitable electrical insulating material. The blocks 38 aresupported by the. lower iron shapes 18, 20 and 22 for the severalheating sections A, B and C, respectively. The bends 26 are eachprovided with an upper projecting lu 39 that extends through aninsulated bus ing 40, carried by one of the iron shapes 19, 21 or 23. Bythis construction, expansion and contraction of the individual pipes 25causes the lugs 39 to move in the bushings 40 as shown in dotted line inFig. 4. The terminal pipes 30 are provided with insulating bushings 41for preventing electrical contactwith the iron shapes through which theyextend.

The heater units are primarily supported by the iron shapes 18, 20 and22. The upper iron shapes 19, 21 and 23 serve primarily to guide andspace the heater units, permitting their expansion and contraction atthe same time. While we have shown pipes 25 as the resistors in thepresent construction, it is to be understood that other commercial formsas bars, rods and the like may be used for the heater units. However,when such other forms are employed, it is impossible to use them forcooling the material. It is also to be understood that for certainpurposes it may be desirable to mount the heater units in horizontalposition or employ spiral shaped units instead. The method hereindisclosed of subjecting spaced points in diiferent portions of a body ofmaterial to a substantially uniform heat transfer per unit of heatingarea is disclosed and claimed in our co-pending application Serial No.483,008 filed September 19, 1930.

We claim 1. The combination with a container, of a plurality of heatingsections disposed circumferentially thereof with the sections axiallyaligned, each of the heating sections constitnting a plurality oflengths of pipe, and means for connecting the pipes to a source ofelectromotive force, said lengths of pipe having means secured theretoand projecting therefrom for both guiding and positioning the pipelengths.

2. The combination with a container, of a plurality of heating sectionsdisposed circumferentially thereof, with the sections axially aligned,each of the heating sections constituting a plurality of lengths of pipeand means for connecting the pipes to a source of fluid, said lengths ofpipe having means secured thereto and projecting therefrom for bothguiding and positioning the pipe lengths.

3; The combination witha container, of a plurality of heating sectionsdispo'ed circumferentially thereof, with the sectionsaxially aligned,each or the heating sections con- ,stltuting a. plurality of lengths ofpipe, and ,means for selectively connecting the pipes to a source ofelectrol'notive force or to a source of fluid, said lengths of pipehaving means secured thereto and projecting therefrom for both guidingand positioning the pipe lengths.

4. The combination with a container, of a temperature control systemcomprising a plurality of circumferentially arranged heating sectionsproviding an unobstructed space within the container and within thesections, each of said sections comprising a plurality of pipe members,and means for controlling the temperature of the several sections, saidpipe members having positioning and guiding means directly carriedthereby.

5. In an electricalheating unit, a plurality of heating elementsconstituted by exposed metallic members of commercial form and aterminal member of exposed metallic material having a cross sectionalarea in excefis of the cross sectional area of the heating elements,whereby the temperature of the ter-- metallic support therefor,comprising a lug, a

bracing member having an opening therein, said lug fitting looselywithin said opening, and an electrical insulator separating the lug andbracing member while permitting longitudinal movement of the lug withinthe opening.

8. The combination with a container, of a heating unit disposed thereinto provide a substantially unobstructed space within and surrounded bythe unit, and guiding means cooperating with such unit intermediate thesame and said space and effective 'for guiding material into the spacewithin the container without injury to said unit.

9. The combination with a container, of a heating unit disposed thereinto provide a substantially unobstructed space within and surrounded bythe unit, and guiding means cooperating with such unit intermediate thesame and said space and eiiective for guiding material into the spacewithin the container without injury to said unit, said unit comprising aplurality of standard commercial shapes connected inend to endrelationship.

10. The combination with a container, of a heating unit disposed thereinto provide a substantially unobstructed space within and surrounded bythe unit, and guiding means cooperating with such unit intermediate thesame and said space and eflective 'for guiding material into the spaceWithin the container without injury to said unit, said unit comprising aplurality of standard pipe fittings and lengths connected in end to endrelationship. v

11. The combination with a container, of a heating unit disposed thereinto provide a substantially unobstructed space within and surrounded bythe unit, andguiding means cooperating with such unit intermediate thesame and said space and effective for guiding material into the spacewithin-the container without injury to said unit, said unit comprising aplurality of standard pipe fittings and lengths connected in end to endrelationship, there being means carried by the pipe lengths forpreventing contact between adjacent lengths.

12. The combination with a. container adapted to receive material to betreated, of a plurality of heating units positioned therein in groupsadapted to actually contact with the material to be treated, each ofsaid groups lying in a definite zone substantially normal to one of theaxes of the container, and means for circulating a cooling mediumthrough such units.

13. The combination with a container adapted to receive material to betreated, of a plurality of heating units positioned therein in groupsadapted to actually contact with the material to be treated, each ofsaid groups lying in a definite zone substantially normal to one of theaxes of the container with adjacent zones in predetermined spacedrelationship and means for circulating a cooling medium through suchunits.

14. The combination with a container adapted to receive material to betreated, of a plurality of heating units positioned therein in groupsspaced axially of the container, each of said groups lying in a definitezone substantially normal to the axis of the container along which thegroups are spaced, and means for individually controlling thetemperature conditions in any of said zones, and connections enablingthe bodily removal of all of said heating units.

15. The combination with a container having material therein to beheated, of an electrical heating unit submerged directly in saidmaterial and in direct contact therewith, said unit providing asubstantially unobstructed space within the same and within thecontainer, and connections enabling the bodily removal of said heatingunit.

16. The combination with a container, of a heating unit comprising aplurality of hollow pipe sections secured in end to end relationship,said. container and pipe sections being constructed for the directreception of and contact with the material to be heated, and connectionsenabling the bodily removal of said heating unit.

17. The combination with a container, of a heating unit removablysupported therein and comprising a plurality of pipe lengthsinterconnected to provide a continuous flow path for the electriccurrent, said container eing constructed for the reception of fluidmaterial to be heated, either prior to or subsequently to the insertionof the heating unit in position therein, and connections for circulatinga cooling medium through said pipe lengths.

18. The combination with a container, of a heating unit comprising aplurality of standard commercial shapes secured in end to endrelationship, said container being constructed for the direct receptionof the material to be heated, each of said heating units providing aplurality of separate heating zones, and means for controlling thetemperature conditions at will in any of said zones, and conthrough saidpipe lengths.

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nections for circulating a cooling medium 19. The combination with acontainer, of a heating unit removably supported therein and comprisinga plurality of pipe lengths interconnected to provide a continuous flowpath for the electric current, said container being constructed for thereception of fluid material to be heated, either prior to orsubsequently to the insertion of the heating unit in position therein,each of said heating units providing a plurality of separate heatingzones, and means for controlllng the temperature conditions at will inany of said zones. a

20. A heating unit, comprising a plurality of snbstantiaily verticallydisposed conductors with adjacent conductors connected by U-shapedportions, insulating means engaging and supporting the tower U-shapedportions, and guiding and insulating means cooperating with the upper Ushaped portions. V

21. A heating unit, comprising a plurality of substantially verticallydisposed conductors with adjacent conductors connected by u shapedportions, insulating means engaging and supporting the lower U-shapedportions, and guiding and insuiating means cooperating with the upperiii-shaped portions, there being means intermediate the ends of saidconductors for maintaining adjacent conductors out of e'iectricalcontact one with the other.

22. A heating unit, comprising a plnraiity of snbstantiaily yerticaliydisposed condoctors with ad iacent conductors connected by U-shapedportions, inmiating means on gaging and wppotting the ion'er iii-shapedportions. and gniding and insniatingmeans cooperating with the upperthshaned portions, there being" means intermediate the. ends ofsaid'condu-ctors to maintaining adjacent conductors out of eiectricaicontact one with the other. said last mentioned means being carried bythe conductors themselves.

Q3. in apparatus for electricaiiy treating bodies of material, means forconfininethe materiai and maintaining it substantiaiiy quiescent, meansfor snh iect'ing said substantialiy quiescent body to iocaliaed hea ingat a pinrahty of spaced points in difierent portions of the body with asubstentiaii v nniiorm heat transfer per unit oi heating area, and means"for subseouentiy subjecting the same points to iocalized cooling.

Q4. eipparatus for heating inateriai, 00m" prising means for confining abody oi" material to be heated, and means for alternately heating thematerial in a pln'raiity of spaced localised zones throughout the bodythereoi with a snbstantiaiiy uniform heat transfer per unit heatingzone, and thereafter cooling the some tones.

@5, for heating materiai,

means for confinin a body of material to be heated, means or heating thematerial in a plurality of spaced localized zones throughout the bodythereof, and means for subsequently subjecting said zones to a coolingtemperature.

- In testimony set our hands.

HANS O. SWOBODA. WILLIAM F. METZGER.

whereof we have hereunto

